Systems and methods for shaping sheet materials that include metallic glass-based materials

ABSTRACT

Systems and methods in accordance with embodiments of the invention advantageously shape sheet materials that include metallic glass-based materials. In one embodiment, a method of shaping a sheet of material including a metallic glass-based material includes: heating a metallic glass-based material within a first region within a sheet of material to a temperature greater than the glass transition temperature of the metallic glass-based material; where the sheet of material has a thickness of between 0.1 mm and 10 mm; where at least some portion of the sheet of material does not include metallic glass-based material that is heated above its respective glass transition temperature when the metallic glass-based material within the first region is heated above its respective glass transition temperature; and deforming the metallic glass-based material within the first region while the temperature of the metallic glass-based material within the first region is greater than its respective glass transition temperature.

CROSS-REFERENCE TO RELATED APPLICATIONS

The current application claims priority to U.S. Provisional ApplicationNo. 61/811,405, filed Apr. 12, 2013, the disclosure of which isincorporated herein by reference.

STATEMENT OF FEDERAL FUNDING

The invention described herein was made in the performance of work undera NASA contract, and is subject to the provisions of Public Law 96-517(35 U.S.C. 202) in which the Contractor has elected to retain title.

FIELD OF THE INVENTION

The present invention generally relates to shaping metallic glass-basedsheet material.

BACKGROUND

Metallic glasses, also known as amorphous alloys, embody a relativelynew class of materials that is receiving much interest from theengineering and design communities. Metallic glasses are characterizedby their disordered atomic-scale structure in spite of their metallicconstituent elements—i.e. whereas conventional metallic materialstypically possess a highly ordered atomic structure, metallic glassmaterials are characterized by their disordered atomic structure.Notably, metallic glasses typically possess a number of useful materialproperties that can allow them to be implemented as highly effectiveengineering materials. For example, metallic glasses are generally muchharder than conventional metals, and are generally tougher than ceramicmaterials. They are also relatively corrosion resistant, and, unlikeconventional glass, they can have good electrical conductivity.Importantly, the manufacture of metallic glass materials lends itself torelatively easy processing in certain respects. For example, themanufacture of a metallic glass can be compatible with an injectionmolding process.

Nonetheless, the manufacture of metallic glasses presents challengesthat limit their viability as engineering materials. In particular,metallic glasses are typically formed by raising a metallic alloy aboveits melting temperature, and rapidly cooling the melt to solidify it ina way such that its crystallization is avoided, thereby forming themetallic glass. The first metallic glasses required extraordinarycooling rates, e.g. on the order of 10⁶ K/s, and were thereby limited inthe thickness with which they could be formed. Indeed, because of thislimitation in thickness, metallic glasses were initially limited toapplications that involved coatings. Since then, however, particularalloy compositions that are more resistant to crystallization have beendeveloped, which can thereby form metallic glasses at much lower coolingrates, and can therefore be made to be much thicker (e.g. greater than 1mm). These metallic glass compositions that can be made to be thickerare known as ‘bulk metallic glasses’ (“BMGs”).

In addition to the development of BMGs, ‘bulk metallic glass matrixcomposites’ (BMGMCs) have also been developed. BMGMCs are characterizedin that they possess the amorphous structure of BMGs, but they alsoinclude crystalline phases of material within the matrix of amorphousstructure. For example, the crystalline phases can exist in the form ofdendrites. The crystalline phase inclusions can impart a host offavorable materials properties on the bulk material. For example, thecrystalline phases can allow the material to have enhanced ductility,compared to where the material is entirely constituted of the amorphousstructure. BMGs and BMGMCs can be referred to collectively as BMG-basedmaterials. Similarly, metallic glasses, metallic glasses that includecrystalline phases of material, BMGs, and BMGMCs can be referred tocollectively as metallic glass-based materials or MG-based materials.

Although considerable advances have been made in the development ofMG-based materials, they have yet to be developed to an extent wherethey can truly be implemented as viable, widespread engineeringmaterials. Recently, efforts have been made to develop MG-basedfeedstock that is in the form of conventional sheet metal, e.g. a sheetof material having a thickness of between approximately 0.1 mm andapproximately 10 mm, and being substantially planar otherwise. It isbelieved that such ‘MG-based sheet materials’ can lend themselves toconventional manufacturing processes, and thereby facilitate thewidespread implementation of MG-based materials.

SUMMARY OF THE INVENTION

Systems and methods in accordance with embodiments of the inventionadvantageously shape sheet materials that include metallic glass-basedmaterials. In one embodiment, a method of shaping a sheet of materialincluding a metallic glass-based material includes: heating a metallicglass-based material within a first region within a sheet of material toa temperature greater than the glass transition temperature of themetallic glass-based material; where the sheet of material has athickness of between approximately 0.1 mm and approximately 10 mm; whereat least some portion of the sheet of material does not include metallicglass-based material that is heated above its respective glasstransition temperature when the metallic glass-based material within thefirst region is heated above its respective glass transitiontemperature; and deforming the metallic glass-based material within thefirst region while the temperature of the metallic glass-based materialwithin the first region is greater than its respective glass transitiontemperature.

In another embodiment, the sheet of material has a thickness of betweenapproximately 0.1 mm and approximately 3 mm.

In still another embodiment, the temperature of the metallic glass-basedmaterial within the first region is maintained below its crystallizationtemperature when it is heated above the glass transition temperature.

In yet another embodiment, at least a majority of the sheet of material,as measured by volume, does not include metallic glass-based materialthat is heated above its respective glass transition temperature whenthe metallic glass-based material within the first region is heatedabove its respective glass transition temperature.

In still yet another embodiment, heating the metallic glass-basedmaterial within the first region is accomplished using one of: inductionheating, frictional heating, and a heated fluid.

In a further embodiment, deforming the metallic glass-based materialwithin the first region is accomplished by pressing a shaping tool intothe sheet of material.

In a still further embodiment, a method of shaping a sheet of materialincluding a metallic glass-based material includes: subjecting a sheetof material including a metallic glass-based material to direct contactwith a heated fluid so as to raise the temperature of at least someportion of the metallic glass-based material to a temperature that isabove its glass transition temperature; where the sheet of material hasa thickness between approximately 0.1 mm and 10 mm; and deforming themetallic glass-based material that has been heated by the heated fluidto a temperature above its glass transition temperature.

In a yet further embodiment, the sheet of material is betweenapproximately 0.1 mm and 3 mm.

In a still yet further embodiment, the metallic glass-based materialthat is heated above its glass transition temperature because of theheated fluid is maintained at a temperature lower than itscrystallization temperature.

In another embodiment, deforming the metallic glass-based material thathas been heated by the heated fluid is accomplished by using the heatedfluid to deform the sheet of material.

In yet another embodiment, deforming the metallic glass-based materialthat has been heated by the heated fluid is accomplished by pressing ashaping tool into the sheet of material as it is supported, at least inpart, by the heated fluid.

In still another embodiment, a method of shaping a sheet of materialincluding a metallic glass-based material includes: moving a surfacerelative to a sheet of material including a metallic glass-basedmaterial while the surface and the sheet of material are in directcontact so as to frictionally heat the metallic glass-based materialwithin the sheet of material above its glass transition temperature;where the sheet of material has a thickness of between approximately 0.1mm and approximately 10 mm; deforming the metallic glass-based materialthat has been heated by the frictional heating to a temperature aboveits glass transition temperature.

In still yet another embodiment, the sheet of material has a thicknessof between approximately 0.1 mm and approximately 3 mm.

In a further embodiment, the metallic glass-based material that has beenheated by the frictional heating is maintained at a temperature lowerthan its crystallization temperature during the frictional heating.

In a still further embodiment, moving the surface relative to the sheetof material includes rotating the surface relative to the sheet ofmaterial so as to frictionally heat it.

In a yet further embodiment, deforming the metallic glass-based materialis accomplished by pressing the surface into the sheet of material.

In a still yet further embodiment, deforming the metallic glass-basedmaterial is accomplished by pressing the surface into the sheet ofmaterial so that it conforms to the shape of a mold cavity.

In another embodiment, deforming the metallic glass-based material isaccomplished by using pressurized gas.

In still another embodiment, a method of shaping a sheet of materialincluding a metallic glass-based material includes: deforming a metallicglass-based material within a sheet of material at a temperature lowerthan the glass transition temperature of the metallic glass-basedmaterial, the metallic glass-based material having a volume fraction ofcrystalline phase greater than approximately 30% and a fracturetoughness greater than approximately 80 MPa·m^(1/2); where the sheet ofmaterial has a thickness of between approximately 0.1 mm andapproximately 10 mm.

In yet another embodiment, the metallic glass-based material has avolume fraction of crystalline phase of greater than approximately 40%and a fracture toughness greater than approximately 100 MPa·m^(1/2).

In still yet another embodiment, the sheet of material has a thicknessthat is less than approximately three times the size of the plastic zoneradius of the metallic glass-based material.

In a further embodiment, the sheet of material has a thickness that isless than approximately one-third the size of the plastic zone radius ofthe metallic glass-based material.

In a still further embodiment, the sheet of material has a thickness ofbetween approximately 0.1 mm and approximately 3 mm.

In a yet further embodiment, deforming the metallic glass-based materialis accomplished using a pressing tool.

In a still yet further embodiment, the method further includes removingportions of the sheet of material in a periodic fashion; and deformingthe sheet of material that no longer includes the removed portions so asto form a cellular structure.

In another embodiment, deforming the sheet of material is accomplishedusing a punch and die.

In still another embodiment, the metallic glass-based material isZr_(55.3)Ti_(24.9)Nb_(10.8)Cu_(6.2)Be_(2.8).

In yet another embodiment, a cellular structure includes a metallicglass-based material having a volume fraction of crystalline phasegreater than approximately 30% and a fracture toughness greater thanapproximately 80 MPa·m^(1/2).

In still yet another embodiment, the metallic glass-based material has avolume fraction of crystalline phase greater than approximately 40% anda fracture toughness greater than approximately 100 MPa·m^(1/2).

In a further embodiment, the metallic glass-based material isZr_(55.3)Ti_(24.9)Nb_(10.8)Cu_(6.2)Be_(2.8).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a method of shaping a sheet material including ametallic glass-based material by instituting localized thermoplasticdeformation in accordance with an embodiment of the invention.

FIG. 2 illustrates the temperature profile of a sheet of materialincluding a metallic glass-based material when the sheet of material issubjected to localized heating in accordance with an embodiment of theinvention.

FIGS. 3A-3B depict shaping a sheet material including a metallicglass-based material by instituting localized thermoplastic deformationin accordance with an embodiment of the invention.

FIGS. 4A-4F illustrate shaping a sheet material including a metallicglass-based material into a pot-shaped structure by institutinglocalized thermoplastic deformation in accordance with an embodiment ofthe invention.

FIGS. 5A-5C illustrate using a heated shaping tool to implementlocalized thermoplastic deformation in accordance with an embodiment ofthe invention.

FIGS. 6A-6B illustrate using a line contact heater to implementlocalized thermoplastic deformation in accordance with an embodiment ofthe invention.

FIG. 7 illustrates a method of shaping a sheet material including ametallic glass-based material by using a heated fluid to heat themetallic glass-based material in accordance with an embodiment of theinvention.

FIGS. 8A-8C illustrate using a heated fluid to shape a sheet of materialincluding a metallic glass-based material in accordance with anembodiment of the invention.

FIGS. 9A-9B illustrate shaping a sheet of material including a metallicglass-based material using a bed of heated fluid in accordance with anembodiment of the invention.

FIG. 10 illustrates a method of shaping a sheet material including ametallic glass-based material by using frictional heating to heat themetallic glass-based material in accordance with an embodiment of theinvention.

FIGS. 11A-11D illustrate frictionally heating a sheet of materialincluding a metallic glass-based material so as to shape it inaccordance with an embodiment of the invention.

FIGS. 12A-12B illustrate frictionally heating a sheet of materialincluding a metallic glass-based material so as to shape it and using amold cavity to support the shaping process in accordance with anembodiment of the invention.

FIGS. 13A-13C illustrate frictionally heating a sheet of materialincluding a metallic glass-based material, and using a separatemechanism to shape the heated sheet of material.

FIG. 14 depicts a DH1 metallic alloy that has be cold formed inaccordance with an embodiment of the invention.

FIG. 15 illustrates a method of cold-forming a sheet material includinga metallic glass-based material in accordance with an embodiment of theinvention.

FIGS. 16A-16C depict pressing a sheet of material including a metallicglass-based material at a temperature less than the glass transitiontemperature of the metallic glass-based material in accordance withembodiments of the invention.

FIGS. 17A-17B depict cellular structures that can be created usingcold-forming techniques in accordance with embodiments of the invention.

FIG. 18 illustrates cold-forming a sheet of material including ametallic glass-based material so as to form a cellular structure inaccordance with an embodiment of the invention.

DETAILED DESCRIPTION

Turning now to the drawings, systems and methods for advantageouslyshaping sheet materials that include metallic glass-based materials areillustrated. In many embodiments, a method of shaping a sheet ofmaterial that includes a metallic glass-based material includes locallyheating a region of the sheet of material, the region including ametallic glass based-material, such that the temperature of the metallicglass based-material that is within the region is elevated to above itsglass transition temperature, and deforming the heated metallicglass-based material into a desired configuration. In numerousembodiments, the sheet of material has a thickness of betweenapproximately 0.1 mm and 10 mm. In many embodiments, a method of shapinga sheet of material that includes a metallic glass-based materialincludes subjecting the sheet of material to direct contact with aheated fluid so as to raise the temperature of at least some portion ofthe metallic glass-based material to a temperature above its glasstransition temperature, and deforming the metallic glass-based materialwhile it is heated above its glass transition temperature. In numerousembodiments, a method of shaping a sheet of material that includes ametallic glass-based material includes moving a surface relative to thesheet of material while the surface and the sheet of material are indirect contact so as to frictionally heat the metallic glass-basedmaterial to a temperature above its glass transition temperature, anddeforming the metallic glass-based material that has been heated by thefrictional heating to a temperature above its glass transitiontemperature.

The efforts to develop metallic glass-based materials so that they canmore viably be incorporated as engineering and/or design materials hasled to the development of metallic glass-based materials in the form ofconventional sheet metal. It is believed that metallic glass-basedmaterials in this form factor can more easily lend themselves toconventional shaping processes, and can thereby promote theirpracticality. For example, metallic glass-based materials in the shapeof conventional sheet metal can act as feedstock for subsequent shapingprocesses, e.g. those commonly used to form conventional metalliccomponents. As one example, Prest et al. disclose a method for formingamorphous alloy sheets including pouring molten metal so that it forms asheet, floating the sheet of molten metal on a second molten metal,cooling the sheet of molten metal to form a metallic glass, andannealing the sheet without deteriorating its metallic glass qualitiesin U.S. Pat. No. 8,485,245. The disclosure of U.S. Pat. No. 8,485,245 ishereby incorporated by reference in its entirety.

Although sheets of metallic glass-based material have been formed, theyare typically still not entirely compatible with conventional shapingprocesses. For example, while metallic glasses may be relatively toughcompared to conventional glasses, they may not be tough enough towithstand a conventional folding operation, e.g. one that a conventionalmetal may be able to withstand. In essence, sheets of metallicglass-based are not universally compatible with conventionalforming/shaping operations. Instead, methods for forming a metallicglass-based sheet material typically involve heating the sheet so thatit may be thermoplastically formed/shaped. For example, in U.S. Pat. No.8,613,815, Johnson et al. disclose using a rapid capacitor discharge toheat an amorphous alloy sample above its glass transition temperatureand simultaneously thermoplastically forming/shaping the sample. Thedisclosure of U.S. Pat. No. 8,613,815 is hereby incorporated byreference in its entirety. However, it is not clear that using a rapidcapacitor discharge can be effective for example to heat a sheet ofmaterial based on a bulk metallic glass matrix composite that includescrystalline phases beyond some threshold extent. Instead, thecrystalline inclusions may inhibit the heating effect of the rapidcapacitive discharge.

Additionally, Jan Schroers et al. have disclosed the thermoplastic blowmolding of metallic glass sheet materials to form/shape them; thesetechniques essentially regard the heating of the metallic glass sheetabove the glass transition temperature, and thereafter shaping themusing conventional blow molding techniques. Nonetheless, the techniquespresently known for shaping metallic glass-based sheet materials may notbe inefficient and non-optimal in a variety of circumstances.Accordingly, the instant application discloses further methods that canmore efficiently shape metallic glass sheet material, and can therebymake metallic glass-based material an even more viable option as anengineering material.

For example, in some embodiments, metallic glass-based sheet material isheated only where deformation is to occur (as opposed to the entiremetallic glass-based sheet material being heated). In this way, the riskof adversely impacting the material properties of the sheet materialwith unnecessary heating can be mitigated. In a number of embodiments, aheated hydraulic fluid is used to heat a metallic glass-based sheetmaterial above its glass transition temperature; the hydraulic fluid canthen be used in the shaping/forming of the metallic glass sheetmaterial. Using heated hydraulic fluid in the shaping of metallic glasssheet material can be an effective shaping method insofar as the fluidcan provide substantial pressure to the metallic glass sheet materialand cause it to conform to unique mold cavity geometries that may bedifficult to accomplish otherwise. In several embodiments, a metallicglass sheet material is frictionally heated to above its glasstransition temperature; the tool causing the frictional heating may thenbe used to shape the metallic glass sheet material. In this way, coolingcan be quickly initiated by removing the tool. Quickly initiating thecooling stage is important in maintaining the amorphous structure of themetallic glass-based material. In many embodiments, a method of shapinga metallic glass sheet material involves shaping the metallicglass-based sheet material at room temperature—this can be achieved whenthe metallic glass-based sheet material has the requisite materialsproperties. These processes are now discussed in greater detail below.

Shaping Processes Incorporating Localized Thermoplastic Deformation

In many embodiments, metallic glass-based sheet materials are shaped byheating only those regions of the sheet where thermoplastic deformationis to take place. In this way the unnecessary heating of the remainderof the sheet material can be avoided. Avoiding the unnecessary heatingof the remainder of the sheet material can confer a number of benefits.For example, in general, heating metallic glass-based materials to atemperature where they can be thermoplastically formed (e.g. above theirglass transition temperatures) carries with it the risk of inadvertentlyheating the metallic glass-based materials to a temperature above thecrystallization temperature, thereby causing the metallic-glass basedmaterial to crystallize and lose its glass-like qualities. Moreover,heating metallic glass-based materials additionally carries the risk ofcausing unwanted oxidation. Accordingly, by avoiding unnecessarilyheating the sheet material where heating is not required, the risk ofadversely affecting the material properties is correspondingly reduced.Moreover, avoiding the unnecessary heating can allow the shaping processto be more energy efficient, e.g. energy is not needed to heat theentire sheet material—only those portions that embody the deformation.

FIG. 1 illustrates a process for shaping a metallic glass-based sheetmaterial that includes locally heating and deforming the sheet materialin accordance with embodiments of the invention. In particular, theprocess 100 includes heating 102 a metallic glass-based material that iswithin a region within a sheet of material to a temperature greater thanthe glass transition temperature of the metallic glass based material.Note that the sheet of material can be of any dimensions. As can beappreciated, sheet materials are typically substantially planar and havea characteristic thickness. The characteristic thickness can be of anysuitable dimensions. In many embodiments, sheets having a thickness ofbetween approximately 0.1 mm and approximately 10 mm are implemented inthe process. In numerous embodiments, sheets having a thickness ofbetween approximately 0.1 mm and 3 mm are implemented. Notably, in manyembodiments, the sheet of material is entirely constituted of a singlemetallic glass-based material. In a number of embodiments, the sheet ofmaterial is constituted of a first metallic glass-based material and atleast a second metallic glass-based material. In several embodiments,the sheet of material is constituted of a metallic glass-based materialin conjunction with another material. Generally, any suitable sheet ofmaterial that includes a metallic-glass based material can beimplemented in accordance with embodiments of the invention.

Additionally, the metallic glass-based material within a region can beheated 102 using any suitable technique in accordance with embodimentsof the invention. For example, in many embodiments, the metallicglass-based material within the region is heated using inductionheating. In a number of embodiments, the metallic glass-based materialwithin the region is heated using a heated fluid. In many embodiments,the metallic glass-based material is heated frictionally. In general,any suitable method of heating the metallic glass-based material withinthe region can be implemented.

In numerous embodiments, at least some portion of the sheet material ismaintained at a temperature lower than the glass transition temperatureof the heated metallic-glass based material. In several embodiments, atleast some of the metallic glass-based material within the sheet ofmaterial is at a temperature lower than its respective glass transitiontemperature when the metallic glass-based material within the region isheated above its respective glass transition temperature. In manyembodiments, at least some portion of the sheet material is maintainedat a lower temperature than the lowest glass transition temperatureamongst any of the metallic glass-based materials that are present inthe sheet of material. In a number of embodiments, the majority of thesheet material (e.g. as measured by volume, or alternatively, by surfacearea) does not include metallic glass-based material that is above itsrespective glass transition temperature when the metallic glass-basedmaterial within the region is heated to above its glass transitiontemperature. In several embodiments, the majority of the sheet ofmaterial is maintained at a temperature lower than the lowest glasstransition temperature of any of the metallic glass-based materials thatare present in the sheet of material. In many embodiments, thetemperature of the metallic glass-based material is kept below thecrystallization temperature.

FIG. 2 depicts a schematic illustration of the temperature as a functionof location along a length of a sheet of material that is entirelyconstituted of a single metallic glass-based material. In particular, itis illustrated that only a certain region of the sheet of material isheated above the glass transition temperature of the metallicglass-based material. Thus, as can be appreciated, this region of thesheet can be thermoplastically formed, whereas the other portions arenot amenable to thermoplastic forming.

Returning back to FIG. 1, the method 100 further includes deforming 104the metallic glass based-material within the region while it has beenheated 102 above the glass transition temperature of the metallicglass-based material. In other words, the method 100 involvesthermoplastically forming the sheet of material. The metallic glassbased material can be deformed 104 in any suitable way in accordancewith embodiments of the invention. For example, the metallic glass-basedmaterial can be folded, stamped, corrugated, etc. In general, any methodof contorting the heated metallic glass-based material in the region canbe implemented. Thus, using this method, metallic glass-based sheetmaterial can be more efficiently shaped.

FIGS. 3A and 3B depict the local heating and deformation of a sheetmaterial in accordance with embodiments of the invention. In particular,FIG. 3A depicts a sheet of material 302 including a first region 304,that itself includes a metallic glass-based material. The first region304 is heated by an induction coil 306 so that the temperature of theresiding metallic glass-based material is elevated to above its glasstransition temperature. FIG. 3B depicts a tool 308 that is used to applyan upward force on the sheet of material 302 while the first region 304is heated so as to cause the thermoplastic deformation of the metallicglass-based material in the region 304 in accordance with embodiments ofthe invention. Note that in the illustrated embodiment, the remainder ofthe sheet of material is not unnecessarily heated as it is not intendedto be thermoplastically formed. Of course, as can be appreciated, whileFIGS. 3A and 3B depict an induction coil heater, the metallicglass-based material within the region can be heated using any suitabletechnique in accordance with embodiments of the invention.

Although FIGS. 3A-3B depict the folding of a metallic glass-based sheetmaterial, a sheet of material including metallic glass-based materialscan be thermoplastically formed in any suitable way in accordance withembodiments of the invention. For example, FIGS. 4A-4E illustrate thatpot shaped structures can be formed from metallic glass-based sheetmaterials in accordance with embodiments of the invention. Inparticular, FIG. 4A depicts the general shape of pots, which can becharacterized by a principal bend adjoining the bottom of the pot andits walls. FIG. 4B depicts the general setup that can be used to form apot-shaped structure in accordance with embodiments of the invention. Inparticular, FIG. 4B depicts a metallic glass-based sheet material 402being supported by a cylindrical structure 408 that is thermallyconductive. The sheet of material 402 is also held in place by structure410. Induction coils 406 are used to heat the thermally conductivecylindrical structural 408. Regions 404 are highlighted as the targetareas for the thermoplastic deformation. The Induction coils 406 areused to heat the thermally conductive structure 408 so that the region404 of the sheet of material 402 can be heated to above the glasstransition temperature. Bear in mind that FIG. 4B illustrates across-sectional view of the set up—as can be appreciated, theillustration is meant to communicate circular geometries. For purposesof clarity, FIG. 4C depicts an isometric view of setup. The structure410 and the induction coils 406 are omitted in FIG. 4C for purposes ofclarity.

FIG. 4D depicts that a cylindrical tool 412 is used to shape themetallic glass based sheet material 402 while the region 404 has beenhas been heated so that its constituent metallic glass-based material isabove its glass transition temperature. In particular, the cylindricaltool 412 is pressed into the sheet material to shape it. The heatedregion 404 can accommodate the thermoplastic shaping that can enable thecreation of the structure.

FIG. 4E depicts the shape of the sheet material 402 after it has beentreated, and FIG. 4F depicts that the remainder of the sheet materialmay be separated from the pot-shaped structure.

In some embodiments, the tool that is used to heat metallic glass-basedmaterial within a sheet is also used to shape the sheet material. FIGS.5A-5C illustrate a method of shaping metallic glass-based sheetmaterial, whereby a tool in the shape of a parabolic head is used toboth heat the metallic glass-based material within a sheet to above itsglass transition temperature and shape metallic glass-based sheetmaterial. In particular, FIG. 5A depicts the metallic glass-based sheetmaterial 502 along with a parabola-shaped tool 506 that is used to shapethe metallic glass-based sheet material. The tool 506 is also used toheat a region of the sheet of material to a temperature above the glasstransition temperature of its constituent metallic glass-based material.For example, the tool 506 itself can be heated, and thereby heat thesheet of material through conduction. Alternatively, the parabola-shapedtool 506 can be spun about its central axis against the sheet ofmaterial to generate frictional heating, and thereby heat the metallicglass-based sheet material 502 to the requisite temperature. FIG. 5Bdepicts that the tool 506 has been used to thermoplastically shape thesheet of material 502 as it has been heated above the requisite glasstransition temperature. Note that the tool 506 is not in direct contactwith any other portion of the sheet of material so that the remainingportions of the sheets of material are not necessarily heated above theaforementioned glass transition temperature. FIG. 5C depicts that, asbefore, the desired shape can be separated from the sheet material 502.

While the above illustrations depict that a cylindrical tool having arelatively large diameter is used to shape the metallic glass-basedsheet material, it should be clear that a tool of any shape can be usedto shape the sheet material object. For example, in some embodiments aline contact heater is used to heat and thermoplastically shape thesheet material. FIGS. 6A-6B depict shaping a sheet material with a linecontact heater in accordance with embodiments of the invention. Inparticular, FIG. 6A depicts a sheet of material 602 supported bystructures 610, 612. A line contact heater 608 is the tool that is usedto form the sheet of material 602. The line contact heater is heatedwith induction coils 606. FIG. 6B depicts the shaping of the sheet ofmaterial 602 using the line contact heater 608. Note that the finalshape of the shaped sheet metal will depend on a variety of parametersincluding: to what extent the metallic glass-based material was heatedabove its glass transition temperature, the force with which the linecontact heater is applied to the sheet material, and the length of timethat the sheet material is exposed to the line contact heater. As can beappreciated, any of these parameters can be varied to control the finalshape of the sheet material.

The localized thermoplastic shaping techniques described above can beimplemented and modified in any of a variety of ways in accordance withembodiments of the invention. For example, any of a variety of shapingtools can be used to shape heated metallic glass-based sheet materials.In some embodiments, a plurality of regions within a sheet of materialincluding metallic glass-based materials are simultaneouslythermoplastically shaped. It should also be appreciated that the sheetof material can include any suitable metallic glass-based material inaccordance with embodiments of the invention, and is not limited to aparticular subset of metallic glass-based materials. Generally, any of avariety of modifications to the above described techniques can beimplemented in accordance with embodiments of the invention.Additionally, while the above discussion has focused on advantageouslyshaping sheet material including metallic glass-based materials usinglocalized thermoplastic forming techniques, in many embodiments, fluidsare used to thermoplastically form a sheet of material includingmetallic glass-based materials. These processes are now described ingreater detail below.

Using Fluids in the Thermoplastic Shaping of Sheet Materials

In many embodiments, fluids are used to thermoplastically shape a sheetof material that includes a metallic glass-based material. In a numberof embodiments, heated fluids are used to elevate the temperature of theconstituent metallic glass-based material to above its respective glasstransition temperature. Any fluid capable of heating a sheet of materialincluding metallic glass-based material above the glass transitiontemperature of the metallic glass-based material can be utilized inaccordance with embodiments of the invention. For example, in someembodiments, molten metal is used as the heating fluid. In a numerousembodiments, a conventional hydraulic fluid is used. In severalembodiments, a heating oil is used. In a number of embodiments, aheating gas is used. In general, any suitable fluid that can heat asheet of material including metallic glass-based materials can beutilized in accordance with embodiments of the invention. In manyinstances, it is simply required that the fluid be able to heat thesheet material to a temperature that is greater than approximately 350°C. The heated fluid can thereafter be used to apply pressure to thesheet of material and thereby cause it to conform to the shape of atool. Using fluids in this manner can be advantageous insofar as fluidscan more uniformly apply heat and pressure to a sheet of materialagainst a tool irrespective of the tool geometry. For example, where asheet of material is to be shaped by a curved tool, the liquid can moreeasily cause it to uniformly conform to the shape of the curvature. Ingeneral, the fluid can be used in conjunction with any shaping tool toshape the sheet of material in accordance with embodiments of theinvention.

FIG. 7 depicts one method of shaping a sheet of material including ametallic glass-based material using a heated fluid in accordance withembodiments of the invention. In particular the method 700 includesheating 702 metallic glass-based material within a sheet of materialusing a fluid to a temperature greater than the glass transitiontemperature of the metallic glass-based material. As alluded to above,any suitable heating fluid can be implemented. The method 700 furtherincludes deforming 704 the metallic glass-based material that has beenheated by the heated fluid. Again, as previously alluded to, thedeformation 704 can be achieved using any suitable technique.

For example, in some embodiments, a shaping tool having a semi-circularcross section is used to shape a sheet of material including a metallicglass-based material in accordance with embodiments of the invention.FIGS. 8A-8C depict how such a heated fluid can be used in conjunctionwith such a shaping tool to shape a metallic glass-based sheet materialin accordance with embodiments of the invention. In particular, FIG. 8Aillustrates an initial setup that includes a sheet of material 802including a metallic glass-based material, a fluid 804 that heats thesheet of material 802 to above the glass transition temperature of theconstituent metallic glass-based material so that it can bethermoplastically shaped, and a mold 806 which shapes the sheet ofmaterial 802. The sheet of material 802 is held in place by supportingblocks 808. FIG. 8B depicts the thermoplastic shaping of sheet ofmaterial 802 by using the fluid 804 to apply sufficient pressure (e.g.,10,000 psi) to cause the sheet 802 to conform to the shape of the mold806 after the temperature of the constituent metallic glass-basedmaterial is elevated to above its glass transition temperature. Asalluded to above, the fluid can uniformly apply pressure to the sheetagainst the mold 806, and thereby more precisely cause the formation ofthe desired shape. FIG. 8C depicts the shape of the sheet 802 after theprocess. As mentioned above, any suitable heating fluid can be used inaccordance with this process. Additionally, although a mold having asemi-circular shape has been illustrated, it should clear that anyshaping tool can be incorporated. Indeed, the interchangeability of theshaping tools is one of the advantages of the described process.

While FIGS. 8A-8C depict using a liquid to force a sheet of materialagainst a shaping tool, in many embodiments a shaping tool is used toforce a sheet of material against a heated fluid. For example, FIGS.9A-9B depict shaping a sheet of material including metallic glass-basedmaterial by using a shaping tool to force the sheet of material againsta bed of heated liquid in accordance with embodiments of the invention.In particular, FIG. 9A depicts an initial setup that includes a sheet ofmaterial 902 including metallic glass-based material disposed above abed of heated fluid 904. The container housing the heated fluid includesreservoir regions 908. A shaping tool 906 is seen above the sheet ofmaterial 902. FIG. 9B depicts that she shaping tool 906 forces the sheetof material 902 into the bed of heated fluid 904 to shape it. As before,the heated fluid 904 can uniformly apply pressure to the sheet ofmaterial 902 against the shaping tool 906. As can be appreciated, theheated fluid elevates the temperature of the metallic glass-basedmaterial within the sheet of material 902 to above the glass transitiontemperature so that it can be thermoplastically formed. Notably, thereservoirs 908 accommodate the displaced fluid and thereby facilitatethe shaping process. Thus, it is demonstrated how the heated fluid cansupport a sheet of material while it is being shaped by a distinctshaping tool.

Of course, it should be appreciated that the above-described processescan be varied in any of a variety of ways in accordance with embodimentsof the invention. For example, as previously mentioned, any of a varietyof fluids can be implemented, and the fluids do not necessarily have tobe liquid—they can be gaseous. Similarly, any of a variety of shapingtools can be used in conjunction with the above-described processes.Additionally, in some embodiments, the fluid does not heat the sheet ofmaterial above the glass transition temperature of the constituentmetallic glass-based material; instead the sheet of material isseparately heated (e.g. using an induction heater), and the fluid isused to thermoplastically shape the separately heated material sheet. Ina number of embodiments, the fluid is used in conjunction with anothermechanism (e.g. an induction heater) to heat the sheet of material abovethe glass transition temperature of the constituent metallic glass-basedmaterial. The sheet of material can thereby be thermoplastically formed.Of course it should be appreciated that the above techniques can beapplied in conjunction with any of a variety of suitable metallicglass-based materials—the process is not limited to a particular subsetof metallic glass-based materials. While the above discussion hasregarded using fluids in conjunction with the thermoplastic shaping of asheet of material including a metallic glass-based material, in manyembodiments, a sheet of material including metallic glass-basedmaterials is heated frictionally above the relevant glass transitiontemperature so that it can be thermoplastically formed. These processesare now discussed in greater detail below.

Shaping Processes Incorporating Frictional Heating

In many embodiments of the invention, a sheet of material includingmetallic glass-based materials is heated frictionally so that they maybe thermoplastically shaped. Incorporating frictional heating inthermoplastic shaping processes can be advantageous insofar as thesubsequent cooling of the material can be initiated efficiently andvirtually immediately with the removal of the friction-causingmechanism. Recall that cooling rates play a vital role in allowing ametallic glass-based material to retain its amorphous structure.Frictional heating can be instituted using any of a variety of processesin accordance with embodiments of the invention. For example, in manyembodiments, a surface is rapidly rotated while in direct contact with asheet of material including a metallic glass-based material so as toraise the temperature of the metallic glass based material above therelevant glass transition temperature. In a number of embodiments,frictional heating is effectuated by translational sliding of a surfacewith the material sheet. In many embodiments, the surface is the shapingtool that is used to thermoplastically shape the material sheet. Ingeneral, any mechanism for frictionally heating the sheet of materialcan be incorporated in accordance with embodiments of the invention.

FIG. 10 depicts one method of shaping a sheet of material including ametallic glass-based material by using frictional heating in accordancewith embodiments of the invention. In particular, the method 1000includes sliding 1002 a surface relative to a sheet of material thatincludes a metallic glass-based material while the surface and the sheetof material are in direct contact so as to frictionally heat themetallic glass-based material to a temperature above its glasstransition temperature. As alluded to above, the relative motion can beachieved in any suitable way including by rotating the surface againstthe sheet of material and by translating the surface against the sheetof material. The method 1000 further includes deforming 1004 themetallic glass-based material that has been heated by the frictionalheating. As can be appreciated, any method of deformation 1004 can beimplemented. For example the surface that causes the friction can bepressed into the sheet of material. In some embodiments, a distinctlydifferent surface (e.g. not the surface that causes friction) is used tocause the deformation. In a number of embodiments a gas is used to causethe deformation. In general, any suitable technique for causing thedeformation can be implemented in accordance with embodiments of theinvention.

FIGS. 11A-11D depict shaping a sheet of material including a metallicglass-based material using frictional heating caused by a shaping toolthat incorporates a parabola-shaped head in accordance with embodimentsof the invention. In particular, FIG. 11A depicts the initial setup forthe process that includes a sheet of material 1102 that itself includesa metallic glass-based material being supported by structures 1110. Theshaping tool 1104 includes a parabola-shaped head, and is shownrotatable about its central axis, so that it can generate the requisitefriction to elevate the temperature of the constituent metallicglass-based material above its glass transition temperature. FIG. 11Bdepicts the direct contact between the shaping tool 1104 and the sheetof material 1102 while the shaping tool 1104 is spinning, so as togenerate frictional heating. FIG. 11C depicts that the shaping tool hasfurther penetrated the sheet of material 1104 because of thethermoplastic shaping process; note that with greater penetration of thesheet of material, there is more surface area in direct contact betweenthe shaping tool 1104 and the sheet of material 1102, andcorrespondingly more frictional heating. FIG. 11D depicts the resultingshape of the sheet of material 1102 after the processing. As can beinferred from the illustrations, frictional heating can be used tolocally thermoplastically shape sheets of material, as the frictionalheating can be relatively localized.

Although the above description and accompanying illustration depicts theusing a shaping tool to shape the metallic glass sheet without thesupport of a mold cavity, in many embodiments a mold cavity is also usedto help shape the sheet of material. FIGS. 12A-12B depict using a moldcavity in conjunction with a cylindrical shaping tool to help shape asheet of material in accordance with embodiments of the invention. Inparticular, FIGS. 12A-10B are similar FIGS. 12A-12C, except they furtherdepict a mold cavity 1212 that accommodates the deformation caused bythe shaping tool.

While the above descriptions have regarded scenarios where the shapingtool is also used to provide frictional heating, in many embodiments thefriction causing mechanism and the shaping mechanism are distinct. Forexample, FIGS. 13A-13C depict that a pressure difference is used tothermoplastically shape a sheet of material after it has beenfrictionally heated. In particular, FIG. 13A depicts an initial setupthat includes a sheet of material 1302 supported by a structure 1310, afriction causing surface 1304, as well as a mold cavity 1312. As before,the friction causing surface is rotatable about its central axis, andcan thereby generate friction. FIG. 13B depicts that the frictioncausing surface 1304 frictionally heats the sheet of material 1302 to atemperature above the relevant glass transition temperature. FIG. 13Cdepicts that an imposed pressure difference between the region outsideof the mold cavity 1312 and the mold cavity can cause the desireddeformation. For example, the region outside the mold cavity can befilled with pressurized gas to cause the sheet material to conform tothe mold cavity 1312. Although, a pressure differential is used to causethe desired shaping, it should be clear that any shaping technique canbe used in conjunction with frictional heating in accordance withembodiments of the invention. For example, a distinct pressing mechanismcan be implemented.

In general, similar to before, the above-described processing techniquescan be modified in any of a variety of ways in accordance withembodiments of the invention. While the above processes have largelyregarded the thermoplastic shaping of metallic glass-based sheetmaterials, in many embodiments, shaping processes for cold-forming sheetmaterials including metallic-glass based materials that includecrystalline inclusions are implemented, and these are now discussed ingreater detail below.

Cold-Forming of Sheet Materials Comprising Metallic-Glass BasedMaterials that Include Crystalline Inclusions

Metallic glass-based materials are typically characterized as somewhatbrittle (at least relative to conventional engineering metals such assteel), and their shaping largely revolves around thermoplasticdeformation. However, in many embodiments of the invention, metallicglass-based materials that include crystalline inclusions undergoshaping procedures at temperatures below the respective glass transitiontemperature. In effect, the crystalline inclusions impart sufficientductility to allow for such ‘cold-forming.’ In many embodiments, theconstituent metallic glass-based material includes greater thanapproximately 30% crystalline inclusions (by volume) and has a fracturetoughness of greater than approximately 80 MPa·m^(1/2). In a number ofembodiments, the constituent metallic glass-based material includesgreater than approximately 40% crystalline inclusions (by volume) andhas a fracture toughness greater than approximately 100 MPa·m^(1/2).These characteristics can impart sufficient toughness to the sheetmaterial to allow it to be cold formed. As an example, FIG. 14 depictsthe cold-forming of a DH1 alloy(Zr_(55.3)Ti_(24.9)Nb_(10.8)Cu_(6.2)Be_(2.8)) in accordance withembodiments of the invention. Note that the material survived thebending without brittle failure. The depicted sheet had a thickness of0.8 mm. In many embodiments, the thickness of the sheet material is lessthan approximately three times the size of the plastic zone radius ofthe constituent metallic glass-based material. In many embodiments, thethickness of the sheet material is less than approximately ⅓ the size ofthe plastic zone radius of the constituent metallic glass-basedmaterial. In essence, contrary to conventional wisdom, metallicglass-based materials can be made to withstand cold-forming operations.

FIG. 15 depicts one method of cold-forming a sheet of material includinga metallic glass-based material in accordance with embodiments. Inparticular, the method 1500 includes deforming 1502 a metallicglass-based material within a sheet of material at a temperature lowerthan the glass transition temperature of the metallic glass-basedmaterial, the metallic glass-based material having a volume fraction ofcrystalline phase greater than approximately 30% and a fracturetoughness greater than approximately 80 MPa·m^(1/2). As mentionedpreviously, these characteristics can impart sufficient toughness to themetallic glass-based material to allow it to survive cold-formingoperations. Additionally, as can be appreciated, any suitablecold-forming operation can be implemented on metallic glass-based sheetmaterials having sufficient toughness. For example, FIGS. 16A-16C depicta pressing operation that can be implemented in accordance withembodiments of the invention. In particular, FIG. 16A depicts theinitial setup that includes metallic glass-based sheet material thatincludes at least approximately 30% crystalline inclusions (by volume)1602, a pressing tool, 1604, supporting structures 1610, 1612, and amold cavity 1614. Importantly, the constituent metallic glass-basedmaterial has a fracture toughness of greater than approximately 80MPa·m^(1/2). FIG. 13B depicts that the press 1602 is used to shape thesheet material 1602 at a temperature less than the glass transitiontemperature of the constituent metallic glass-based material. Thematerial properties of the metallic glass-based sheet material (e.g. itstoughness) allow it to survive the pressing operation. FIG. 16C depictsthat the mold cavity 1614 can move with the press 1604 to relax excesspressure. As can be appreciated, FIGS. 16A-16C are akin to a deepdrawing process.

It should of course be clear that any of a variety of forming operationscan be implemented in accordance with embodiments of the invention. Forexample, in many embodiments, the sheet materials are formed usingstamping tools. In a number of embodiments, they are formed with waterjets. In several embodiments, lasers are used to shape the structures.In general, any of a variety of shaping procedures can be implemented.

Notably, the above-described processes can be used to create any of avariety of geometries. For example, in many embodiments, cellularstructures are created. FIGS. 17A-17B depict cellular geometries thatmay be created by cold-forming sufficiently tough sheet materials thatinclude metallic glass-based materials in accordance with embodiments ofthe invention. Cellular structures are often desired for their energyabsorbing capabilities. Indeed, whereas cellular structures aretypically fabricated from conventional engineering materials, cellularstructures fabricated from tough metallic glass-based materials candemonstrate enhanced energy absorbing traits.

FIG. 18 depicts using a punch and die to form a 3D cellular structure inaccordance with embodiments of the invention. In particular, it isillustrated that a sheet 1802 being constituted of a metallicglass-based material has been pre-formed so that it includes a series ofdiamond-shaped holes, thereby adopting a ‘fence-like’ shape. In otherwords, portions of the sheet material have been removed in a periodicfashion to form the fence-like shape. The portions can be removed usingany suitable technique in accordance with embodiments of the invention.For instance, water jets can be used to carve out the diamond-shapedholes; alternatively, lasers can be used. As can be appreciated, themetallic glass-based material can be any such material having greaterthan approximately 30% crystalline inclusions (by volume) and a fracturetoughness of greater than approximately 80 MPa·m^(1/2). A punch 1804 anddie 1806 are used to add a vertical dimension to the sheet 1802 andthereby create a cellular structure. As can be appreciated, thetoughness of the metallic glass-based material can allow it to withstandthe cold-forming operation. Thus, it is seen that 3D cellular structurescan be efficiently made in accordance with embodiments of the invention.

As can be inferred from the above discussion, the above-mentionedconcepts can be implemented in a variety of arrangements in accordancewith embodiments of the invention. Accordingly, although the presentinvention has been described in certain specific aspects, manyadditional modifications and variations would be apparent to thoseskilled in the art. It is therefore to be understood that the presentinvention may be practiced otherwise than specifically described. Thus,embodiments of the present invention should be considered in allrespects as illustrative and not restrictive.

What claimed is:
 1. A method of shaping a sheet of material including ametallic glass-based material comprising: heating a metallic glass-basedmaterial within a first region within a sheet of material to atemperature greater than the glass transition temperature of themetallic glass-based material; wherein the sheet of material has athickness of between approximately 0.1 mm and approximately 10 mm;wherein at least some portion of the sheet of material does not includemetallic glass-based material that is heated above its respective glasstransition temperature when the metallic glass-based material within thefirst region is heated above its respective glass transitiontemperature; and deforming the metallic glass-based material within thefirst region while the temperature of the metallic glass-based materialwithin the first region is greater than its respective glass transitiontemperature.
 2. The method of claim 1, wherein the sheet of material hasa thickness of between approximately 0.1 mm and approximately 3 mm. 3.The method of claim 2, wherein the temperature of the metallicglass-based material within the first region is maintained below itscrystallization temperature when it is heated above the glass transitiontemperature.
 4. The method of claim 3, wherein at least a majority ofthe sheet of material, as measured by volume, does not include metallicglass-based material that is heated above its respective glasstransition temperature when the metallic glass-based material within thefirst region is heated above its respective glass transitiontemperature.
 5. The method of claim 3, wherein heating the metallicglass-based material within the first region is accomplished using oneof: induction heating, frictional heating, and a heated fluid.
 6. Themethod of claim 3, wherein deforming the metallic glass-based materialwithin the first region is accomplished by pressing a shaping tool intothe sheet of material.
 7. A method of shaping a sheet of materialincluding a metallic glass-based material comprising: subjecting a sheetof material comprising a metallic glass-based material to direct contactwith a heated fluid so as to raise the temperature of at least someportion of the metallic glass-based material to a temperature that isabove its glass transition temperature; wherein the sheet of materialhas a thickness of between approximately 0.1 mm and approximately 10 mm;and deforming the metallic glass-based material that has been heated bythe heated fluid to a temperature above its glass transitiontemperature.
 8. The method of claim 7, wherein the sheet of material isbetween approximately 0.1 mm and 3 mm.
 9. The method of claim 8, whereinthe metallic glass-based material that is heated above its glasstransition temperature because of the heated fluid is maintained at atemperature lower than its crystallization temperature.
 10. The methodof claim 9, wherein deforming the metallic glass-based material that hasbeen heated by the heated fluid is accomplished by using the heatedfluid to deform the sheet of material.
 11. The method of claim 9,wherein deforming the metallic glass-based material that has been heatedby the heated fluid is accomplished by pressing a shaping tool into thesheet of material as it is supported, at least in part, by the heatedfluid.
 12. A method of shaping a sheet of material including a metallicglass-based material comprising: moving a surface relative to a sheet ofmaterial comprising a metallic glass-based material while the surfaceand the sheet of material are in direct contact so as to frictionallyheat the metallic glass-based material within the sheet of materialabove its glass transition temperature; wherein the sheet of materialhas a thickness of between approximately 0.1 mm and approximately 10 mm;deforming the metallic glass-based material that has been heated by thefrictional heating to a temperature above its glass transitiontemperature.
 13. The method of claim 12, wherein the sheet of materialhas a thickness of between approximately 0.1 mm and approximately 3 mm.14. The method of claim 13, wherein the metallic glass-based materialthat has been heated by the frictional heating is maintained at atemperature lower than its crystallization temperature during thefrictional heating.
 15. The method of claim 14, wherein moving thesurface relative to the sheet of material comprises rotating the surfacerelative to the sheet of material so as to frictionally heat it.
 16. Themethod of claim 15, wherein deforming the metallic glass-based materialis accomplished by pressing the surface into the sheet of material. 17.The method of claim 16, wherein deforming the metallic glass-basedmaterial is accomplished by pressing the surface into the sheet ofmaterial so that it conforms to the shape of a mold cavity.
 18. Themethod of claim 14, wherein deforming the metallic glass-based materialis accomplished by using pressurized gas.
 19. A method of shaping asheet of material including a metallic glass-based material comprising:deforming a metallic glass-based material within a sheet of material ata temperature lower than the glass transition temperature of themetallic glass-based material, the metallic glass-based material havinga volume fraction of crystalline phase greater than approximately 30%and a fracture toughness greater than approximately 80 MPa·m^(1/2);wherein the sheet of material has a thickness of between approximately0.1 mm and approximately 10 mm.
 20. The method of claim 19, wherein themetallic glass-based material has a volume fraction of crystalline phaseof greater than approximately 40% and a fracture toughness greater thanapproximately 100 MPa·m^(1/2).
 21. The method of claim 20, wherein thesheet of material has a thickness that is less than approximately threetimes the size of the plastic zone radius of the metallic glass-basedmaterial.
 22. The method of claim 21, wherein the sheet of material hasa thickness that is less than approximately one-third the size of theplastic zone radius of the metallic glass-based material.
 23. The methodof claim 20, wherein the sheet of material has a thickness of betweenapproximately 0.1 mm and approximately 3 mm.
 24. The method of claim 23,wherein deforming the metallic glass-based material is accomplishedusing a pressing tool.
 25. The method of claim 23, further comprising:removing portions of the sheet of material in a periodic fashion; anddeforming the sheet of material that no longer includes the removedportions so as to form a cellular structure.
 26. The method of claim 25,wherein deforming the sheet of material is accomplished using a punchand die.
 27. The method of claim 23, wherein the metallic glass-basedmaterial is Zr_(55.3)Ti_(24.9)Nb_(10.8)Cu_(6.2)Be_(2.8).
 28. A cellularstructure comprising a metallic glass-based material having a volumefraction of crystalline phase greater than approximately 30% and afracture toughness greater than approximately 80 MPa·m^(1/2).
 29. Thecellular structure of claim 28, wherein the metallic glass-basedmaterial has a volume fraction of crystalline phase greater thanapproximately 40% and a fracture toughness greater than approximately100 MPa·m^(1/2).
 30. The cellular structure of claim 28, wherein themetallic glass-based material isZr_(55.3)Ti_(24.9)Nb_(10.8)Cu_(6.2)Be_(2.8).